length(first_stage_issp$residuals)
summary(first_stage_issp)$r.squared

fs_issp <- tidy(first_stage_issp)
fs_issp <- kable(fs_issp, format = "latex", digits = 3, booktabs = TRUE)
writeLines(fs_issp,   file.path(graph_dir, "bell_FS_ISSP.txt"))